Instrument illumination system



United States Patent Ofitiee 3,122,329 Patented Feb. 25, 1964 3,122,32 INSTRUMENT ILLUMINATION SYSTEM Leslie J. Hoffman, Orange, Conm, assignor to United Aircraft Corporation, East Hartford, Conn, a corporation of Delaware Filed July 18, 1961, Ser. No. 124,978 4 Claims. (Cl. 240-816) My invention relates to a miniature lamp base and more particularly to a readily demountable miniature lamp base for use in integral lighting systems on aircraft instruments and the like.

In the prior art the most prevalent technique for illuminating aircraft instrument panels has been the external floodlighting technique in which light comes either from a common external source or from a plurality of individual floodli hting units such as lighting posts or lamps provided with shields. In such installations the size of the lamp assemblies is of little imporatnce since the assemblies are mounted external to the instrument. For various reasons such as the elimination of glare and stray light and the prevention of interference by the lamp assemblies with the observers view, the modern trend is toward integral lighting of instruments in which the lighting system is incorporated within the instrument itself so as to become an integral part of the unit. VJhile this internal or integral lighting technique has provided a satisfactory solution to the problems which existed when the external flood lighting technique was used, it has given rise to problems peculiar to the integral lighting technique.

First, owing to the fact that the lamps and their associated structure are disposed inside the instrument case or panel, the size of the assemblies has become important since only a limited space is available within the instrument case or panel for the lighting installation. Owing to this space limitation, the quantity of illumination provided by commercially available assemblies has not proved satisfactory. In an efiort to avoid this problem, in the prior art external projections have been resorted to to provide sutficie'nt space to locate the lamp assemblies in positions at which they properly illuminate the instrument dials. Such projecting lamp locations require assembly screw caps or cups for retaining the lamp in position. Not only do these projecting caps or cups present a safety hazard but from certain positions they may interfere with the observers view.

Most satisfactory integral illumination systems presently in use employ lamps which are buried within the instrument case. While this arrangement gives satisfactory illumination, it embodies the defect that it becomes necessary to dismount the instrument and disassemble it each time a lamp must be replaced.

I have invented an instrument lamp base which overcomes the defects of lamp assemblies of the prior art pointed out hereinabove. My assembly can readily be installed and removed from the front of the panel as a unit. Wnen installed, the assembly is substantially flush with the front of the instrument panel so that it presents no undesirable projection from the front of the panel. The construction and arrangement of my lamp base is such that it is able to fit into locations which heretofore have been inaccessible to lamp assemblies of the prior art. Owing to this fact, my assembly permits greater flexibility in the application of lamps thus permitting improved illumination of instruments and the like. My lamp base prevents leakage of light from the inside of the panel to a point outside the panel or instrument case. I so construct my assembly that it is not affected by vibrations.

Gne object of my invention is to provide an improved lamp base which can readily and expeditiously be assembled on and dismounted from the instrument panel.

Another object of my invention is to provide a lamp base which can be assembled into locations which are inaccessible to lamp bases of the prior art' A further object of my invention is to provide a lamp base which is substantially flush with the outside surface of the instrument panel.

Still another object of my invention is to provide a lamp base having means for preventing leakage of light from the inside of the instrument panel or case through the base mounting opening.

Yet another object of my invention is to provide a lamp base which is relatively insensitive to vibration.

Other and further objects of my invention will appear from the following description.

In general, my invention contemplates the provision of a miniature lamp base in which a spring of conductive material bearing between a conductive outer surface of the mounting panel and a conductive ring carried by a head formed on the base normally urges detents on a conductive collar carried by the base into recesses formed in a conductive inner surface of the mounting panel. I connect the lamp leads respectively to the conductor ring and to the conductive collar to complete the lamp circuit. In response to rotation of the head, the detents register with slots in the panel to permit the lamp assembly to be readily removed from the panel through the mounting opening.

In the accompanying drawings which form part of the instant specification and which are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views:

FIGURE 1 is a fragmentary sectional view of my lamp base in one application thereof.

FIGURE 2 is a fragmentary plan view of my lamp base.

FIGURE 3 is a fragmentary plan view of my lamp base.

Referring now to the drawings, in one application of my lamp base it is used with an instrument having a case 10 the front 12 of which is formed with a bezel 14 which receives the instrument face glass 16. A suitable seal 18 is disposed between the bezel 14 and the glass 16. The instrument may, for example, include a dial block 29 having a face 22 etched or otherwise treated to provide dial marks 24 with which the instrument pointer 26 cooperates in a manner known to the art. A skirt ring 28 surrounding the block 25 is adapted to be illuminated by light from suitable sources to be described hereinafter to illuminate the edge of the block 20 and to flood the pointer 26 with light. Since this structure of the particular installation in which my lamp base is used forms no part of the invention disclosed herein, it will not be described in detail. The details of an illumination system in which my lamp base can advantageously be used are shown in my copending application Serial No. 37,906, filed June 22, 1960, for an Instrument Illumination System, now Patent No. 3,068,833, issued December 18, 1962.

The instrument case 10 supports a lamp base mounting member 39 formed from a suitable insulating material and having its surfaces photoetched or otherwise coated with layers 32 and 34 of conductive material. In any suitable manner known to the art, a potential is applied across the conductive layers 32 and 34. For purposes of simplicity, I have indicated this arrangement schematically as a battery 36 connected to the layers 32 and 34 by respective conductors 38 and 40. A layer of insulation 42 and a thin layer 44 of fish paper or the like separate the conductive layer 32 from the front 12 of the instrument. It will readily be appreciated that the front 12 could be either the front of an individual instrument case or it could be a panel carrying a plurality of instruments.

I provide the panel or instrument front 12 with an opening 46 which leads into an opening 48 of a somewhat smaller diameter which extends into the inside of the instrument. The body 56 of my lamp base is generally cylindrical in shape and is provided with a recess 52 which receives the illuminating lamp 54. The lamp 54 is of the subminiature type such as those designated in the lighting industry as numbers 666, 680, 634 and 627. In order to hold the lamp 54 firmly within the recess 52 in the body, I fill the recess 52 with a suitable bonding filler 56 in a manner to be described hereinafter. Any suitable bonding material may be employed. For example, I may use Epibond which is the registered trademark of Furane Plastic Inc. for an epoxy adhesive for bonding glass, metal, plastics, rubber and related products.

One end of the body 50 is formed with a head provided with a slot 60 for receiving a screwdriver to permit the assembly to be readily mounted on and disassembled from the panel 12 in a manner to be described hereinafter. I mount a ring 62 formed of a suitable conductive material on the underside of the head 58. It will be noted that the underside of head 58 is provided with a depression 64 at a location adjacent an opening '66 in the wall of the body 50. The ring 62 is so shaped that it conforms to the depression 64 in the under surface of the head 58. A lead 68 from the filament of the bulb 54 extends through the opening 66 and is soldered to the conductive ring 62 in the region of the depression 64. I employ a suitable material such as the Epibond referred to hereinabove for holding the ring 62 to the underside of the head 58.

I employ any suitable material such, for example, as Epibond for securing a collar 70 of conductive material to the body 50 at the end thereof remote from the head 58. I dimple the collar 70 at a pair of diametrically op- ,iposite points for example to provide the collar with a pair of detents 72 and 74. The other lead 76 from the filament of the lamp 54 extends out of the body 50 and over the edge thereof to a point at which it is soldered to the conductive collar 70. Between the ring 62 and the collar 70 the body 50 receives a light blocking washer 78 formed of a suitable opaque conductive material. The washer 78 fits closely around the outside of the body 50 and is free to move therealong. I dispose a coil spring 80 formed from a suitable flat conductive material between the ring 62 and the washer 78. When the parts just described are assembled on the mounting panel 3% detents 72 and 74 engage in respective notches or recesses 82 and 84 formed in the coating 34 and washer '78 is received by a shoulder 86 in the coating 32. The parts are firmly held in this position by spring 80.

When the assembly is to be removed from the mounting panel, the head 58 first is pushed inwardly to move detents 72 and '74 out of the notches 32 and 84 and the head is then turned until the detents 72 and 74 register with grooves 88 and hi formed in the opening 48. The assembly can readily be removed from the panel and a repalacement assembly inserted into the panel. This operation can conveniently be accomplished by use of a screwdriver inserted in the slot 60. It will be appreciated that my lamp base not only permits burned-out bulbs to be replaced with relative ease, but also it permits the col or bulb used to be changed in a convenient and expeditious manner. While I have illustrated only one of my bases in connection with an illumination system, it Will readily be appreciated that as many assemblies are used as are required to give the desired illumination.

In assembling the parts of my lamp base, I first bond the ring 62 to the underside of the head 53 with a suit able epoxy resin. I then assemble the spring 8% an the washer 78 on the body 50. Next I bond the collar 70 to the end of the body 513 remote from the head 58.

4 When this has been done, I fill the recess 52 in the body 50 with epoxy resin making sure that the leads 68 and 76 are in position to be soldered respectively to the ring 62 and to the collar 70. When the resin hardens, the leads 68 and 76 may be soldered in place. My lamp base is now complete and ready for use.

In order to mount the base on the panel 30 the assembly is inserted lamp first into the opening 48 with the detents 72 and 74 passing through grooves 88 and 90. It will be appreciated that before the detents clear the grooves 38 and 90, spring is compressed to urge washer 78 into engagement with the shoulder 86. When the detents clear the grooves 88 and 90, head 58 is rotated through half a revolution to bring detents 72 and 74 into engagement with the recesses or notches 82 and 34. When moved to this position the detents 72 and 74 are urged into the notches 82 and 84 by the action of spring 89. It is to be noted that the diameter of the light blocking washer 78 is greater than a diameter extending between the bases of the grooves 88 and 20 so that it effectively blocks the passage of light through the grooves as well as through the opening 48. This will readily be apparent from an examination of FIGURE 2 of the drawings.

With the base assembled on the panel 30 in this manner the circuit of the lamp 54 is complete from the conductive layer 32 through the washer 78 through the spring 80 to the ring 62 through the lead 68 to the lamp from the lamp through lead 76 to the collar 70 and from the collar 7 3 to the conductive layer 34.

When it is desired to replace the assembly, head 58 is moved inwardly against the action of spring 80 to move the detents 72 and 74 out of the notches 82 and 84 and the assembly is rotated to position the detents adjacent the grooves to permit them to move out along the grooves until the assembly has been withdrawn from the panel. A new assembly may then be mounted on the panel described above.

It will be seen that I have accomplished the objects of my invention. I have provided a miniature lamp base which may readily be mounted on and demounted from an instrument panel or case. This operation does not require demounting of the instruments. My assembly is so constructed that it is substantially flush with the surface of the panel. My assembly eifectively blocks the passage of light from the inside of the panel to the outside. My base may be installed in locations which heretofore were inaccessible to lamp bases of the prior art.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of my claims. It is further obvious that various changes may be made in details within the scope of my claims without departing from the spirit of my invention. It is, therefore, to be understood that my invention is not to be limited to the specific details shown and described.

Having thus described my invention, what I claim is:

1. In an instrument illumination system having a panel provided with an opening extending therethrough, a lamp assembly including in combination a base having a di ameter smaller than the diameter of said opening, a lamp adapted to be energized to provide a source of illumination, means mounting said lamp on said base, a washer movably carried on said base and fitting closely around the periphery of said base, said washer having a diameter greater than the diameter of said opening and meanscomprising a spring bearing between said washer and said base readily detachably mounting said base in said opening, said spring urging said washer to a position over said opening at which the washer blocks the passage of light from said source through said opening.

2. In an instrument illumination system having a panel provided with an opening extending therethrough, a lamp assembly including in combination a base having a diameter smaller than the diameter of said opening, a lamp adapted to be energized to provide a source of i1- lumination, means mountingsaid lamp on said base, means forming a recess on one side of said panel adjacent said opening, a detent carried by said base at one end thereof for cooperation with said recess, a washer movably carried on said base and fitting closely around the periphery of said base, said washer having a diameter greater than the diameter of said opening and adapted to cover the portion of said opening surrounding said base and a spring bearing between said base and said washer detachably mounting said base in said opening and urging said detent into said recess and positioning said washer over said opening to block the passage of light from said source through said opening.

3. In an instrument illumination system having a panel formed with an opening and provided with conductive elements on the respective sides thereof, a lamp assembly including in combination an elongated base formed of insulating material, said base being inserted into said opening, a lamp adapted to be energized to provide a source of illumination, said lamp having a pair of leads, means mounting said lamp on said base, a first conductive member carried by said base at one end thereof, a second conductive member carried by said base at the other end thereof, means connecting said leads to the respective conductive members, means electrically connecting one of said conductive members to one of said conductive elements, and means comprising a spring formed of conductive material and bearing between the other of said conductive elements and said other conductive member for readily detachably retaining said base in said opening while providing electrical connections between said conductive members and the conductive elements.

4. In an instrument illumination system having a panel formed with an opening and provided with conductive elements on the respective sides thereof, a lamp assembly including in combination an elongated base formed of insulating material, said base being inserted into said opening, a lamp adapted to be energized to provide a source of illumination, said lamp having a pair of leads, means mounting said lamp on said base, a first conductive member carried by said base at one end thereof, a second conductive member carried by said base at the other end thereof, means connecting said leads to the respective conductive members, and means comprising a detent formed in one of said conductive members, means forming a recess in one of said conductive elements for receiving said detent and a spring formed of conductive material and bearing between the other conductive element and the other conductive member and readily detachably retaining said base in said opening while providing electrical connections between said conductive members and the conductive elements.

References Cited in the file of this patent UNITED STATES PATENTS 2,171,431 Kollsman Aug. 29, 1939 2,172,765 Kollsman Sept. 12, 1939 2,677,845 MacArthur Apr. 27, 1954 2,987,695 Peak et al. June 6, 1961 

1. IN AN INSTRUMENT ILLUMINATION SYSTEM HAVING A PANEL PROVIDED WITH AN OPENING EXTENDING THERETHROUGH, A LAMP ASSEMBLY INCLUDING IN COMBINATION A BASE HAVING A DIAMETER SMALLER THAN THE DIAMETER OF SAID OPENING, A LAMP ADAPTED TO BE ENERGIZED TO PROVIDE A SOURCE OF ILLUMINATION, MEANS MOUNTING SAID LAMP ON SAID BASE, A WASHER MOVABLY CARRIED ON SAID BASE AND FITTING CLOSELY AROUND THE PERIPHERY OF SAID BASE, SAID WASHER HAVING A DIAMETER GREATER THAN THE DIAMETER OF SAID OPENING AND MEANS COMPRISING A SPRING BEARING BETWEEN SAID WASHER AND SAID BASE READILY DETACHABLY MOUNTING SAID BASE IN SAID OPENING, SAID SPRING URGING SAID WASHER TO A POSITION OVER SAID OPENING WHICH THE WASHER BLOCKS THE PASSAGE OF LIGHT FROM SAID SOURCE THROUGH SAID OPENING. 